This investigation is principally aimed at studying the mechanism of anion exchange reactions of methylmercury and related organomercurials and the base catalyzed exchange of mercaptans with alkylmercury mercaptides (RHgSR). Exchange reactions of active sulfur and the cysteine residues of electron-transferring proteins such as adrenodoxin will also be investigated. The mode of reaction and rate of cleavage of the disulfide (S-S) linkage with organomercurials and other heavy metal cations will also be studied. Substrates will include both model compounds of simple structure and more complex tripeptides. The program also includes the synthesis of a series of sulfur containing crown ethers and their binding interaction with heavy metals. These data will be related to existing ecological problems associated with heavy metal contamination of the environment.